On the inner Double-Resonance Raman scattering process in bilayer graphene

The dispersion of phonons and the electronic structure of graphene systems can be obtained experimentally from the double-resonance (DR) Raman features by varying the excitation laser energy. In a previous resonance Raman investigation of graphene, the electronic structure was analyzed in the framework of the Slonczewski-Weiss-McClure (SWM) model, considering the outer DR process. In this work we analyze the data considering the inner DR process, and obtain SWM parameters that are in better agreement with those obtained from other experimental techniques. This result possibly shows that there is still a fundamental open question concerning the double resonance process in graphene systems.Comment: 5 pages, 3 figure

Transition from Townsend to glow discharge: subcritical, mixed or supercritical

The full parameter space of the transition from Townsend to glow discharge is investigated numerically in one space dimension in the classical model: with electrons and positive ions drifting in the local electric field, impact ionization by electrons ($\alpha$ process), secondary electron emission from the cathode ($\gamma$ process) and space charge effects. We also perform a systematic analytical small current expansion about the Townsend limit up to third order in the total current that fits our numerical data very well. Depending on $\gamma$ and system size pd, the transition from Townsend to glow discharge can show the textbook subcritical behavior, but for smaller values of pd, we also find supercritical or some intermediate ``mixed'' behavior. The analysis in particular lays the basis for understanding the complex spatio-temporal patterns in planar barrier discharge systems.Comment: 12 pages, 10 figures, submitted to Phys. Rev.

On the algebraic K-theory of the complex K-theory spectrum

Let p>3 be a prime, let ku be the connective complex K-theory spectrum, and let K(ku) be the algebraic K-theory spectrum of ku. We study the p-primary homotopy type of the spectrum K(ku) by computing its mod (p,v_1) homotopy groups. We show that up to a finite summand, these groups form a finitely generated free module over a polynomial algebra F_p[b], where b is a class of degree 2p+2 defined as a higher Bott element.Comment: Revised and expanded version, 42 pages

The tidemark of the chondro-osseous junction of the normal human knee joint

The chondro-osseous junction includes the junction between calcified and non-calcified cartilage matrices often referred to as the tidemark. A detailed knowledge of the structure, function and pathophysiology of the chondro-osseous junction is essential for an understanding both of the normal elongation of bones and of the pathogenesis of osteoarthrosis. In this study the molecular anatomy of the tidemark was studied using histochemical techniques, including lectin histochemistry, on blocks of normal cartilage from human knee joints. The tidemark stained with H&E, picro-sirius red, toluidine blue, safranin O and methyl green, but not with alcian blue in the presence of magnesium chloride at 0.05 M or above. It stained with only four lectins, those from Datura stramonium, Maclura pomifera, Erythrina crystagalli and Helix pomatia, out of the 19 used. Therefore, it is rich in collagen and contains hyaluronan, but appears to lack the glycosaminoglycans of 'conventional' proteoglycans and it expresses a very limited and distinctive lectin staining glycoprofile, which is probably attributable to specific glycoproteins. In addition, the tidemark had a distinct microanatomical trilaminate appearance. From all of these results it is clear that this part of the chondro-osseous junctional region is chemically more complex and distinctive than has previously been described